Supported Versions

In general, the advice and documentation regarding WNDR3700v1 and WNDR3700v2 is also valid for WNDR3800. The only differences are with amounts of RAM and flash memory. This WNDR3800 article is rather short, as most of the applicable information can already be found on the WNDR3700 wiki page. There is also a WNDR3800-1CHNAS which will not respond to the normal WNDR3800 images. Applying this patch does create a usable image.

Installation

This device is supported in Backfire 10.03.1 and above. Manually building OpenWrt is not required. Quickest way is to download a precompiled last stable image (Chaos Calmer 15.05), look for wndr3800 factory (SquashFS is recommended):

Basic configuration

Specific configuration

Kernel modules

May be need to install WiFi support packages to use WiFi in the Netgerar WRDN3800. Built-in kernel modules of Backfire don't work with WiFi hardware of WNDR3800. If WiFi can't work, you may try following command of uci:

# opkg update# opkg install kmod-ath9k wpad-mini

Ethernet switch configuration (VLAN)

If you want set up some ports to another 802.1Q VLAN, you should known about ethernet port numbers:

Port number in the switch configuation

Port 0

Port 1

Port 2

Port 3

Port 4

Port 5

Port marked in the case

"4"

"3"

"2"

"1"

"WAN"

CPU port (trunk)

"Port 4" are connected to CPU's eth1 and usually it should not be used in your configuration.

Please remember: Port 5 in tagged mode should be included into each VLAN. Otherwise such VLAN can't be routed (will be isolated from router).

Photos

Opening the case

Note: This will void your warranty!

To remove the cover use a Torx (T8) screwdriver.

There are two screws easily visible on the bottom of the case.

There are four more screws under the rubber feet. The feet are not glued to the plastic and can easily be removed and pushed back into place once reassembled. The feet have rubber tethers, but you can slide them out gently without damaging them, and later you can reinsert them just as easily. Don't forget to put them in a plastic baggie so you don't lose them!

Serial

Internal J1 4-pin connector

Pin Out

Description

Pin1

3.3V

Pin2

TX

Pin3

RX

Pin4

GND

3.3V serial port voltage !!! Is it need to use 3.3V serial adapter, for example, with PL2303 chip. (You may modify usb cable for mobile phone.)

Recovery flash in failsafe mode

If you happen to brick your router, do not fear. You can use TFTP file transfer to flash the router with a new firmware.

You need:

A TFTP client for your computer. There are both command-line tools and GUI versions available.

Your computer must have an IP address from the 192.168.1.x network, as the router failsafe mode defaults to 192.168.1.1.

A new firmware to flash in. Either an original Netgear firmware or an Openwrt "factory.img" firmware. "Sysupgrade" version will not work.

Access to router's reset button

Configure your ethernet connection (on the client machine you're using to configure the WNDR3800) using a static IP as 192.168.1.2, netmask 255.255.255.0. (The WNDR3800 in factory reset mode is going to come up as 192.168.1.1.)

Connect your computer to one of the LAN (not WAN) ports on the router.

Start a continuous ping from your client computer to 192.168.1.1 (Linux and Mac OS ping will continue until stopped by default; Windows ping by default sends 4 pings and then stops, so use "ping -t" under Windows); probably nothing will answer these pings yet, but you can use the output to tell you when the router is ready in the next couple steps.

Power the router off.

Hold down the factory reset button on the bottom of the case. Now turn the router back on while continuing to hold the factory reset button…

Wait until the router is listening on 192.168.1.1 (this takes 45-60 seconds; to confirm, you can ping 192.168.1.1, and see if it responds; it's best to start a sequence of ping requests above, before your hands get busy with the factory reset button).

Release the factory reset button. (If you happen to have a serial cable connected, you'll see that the system is in firmware recovery mode and that it will be waiting for you to upload firmware. But you don't need the serial cable at all.)

Run a tftp CLIENT on your computer (enter no hostname on the command line), set transfer mode to binary and retransmit timeout to one second (optional), next put firmware image to router.

For the linux tftp client enter the following (note "rexmt 1"! Some people do not see "1" and enter "binary" as the value for rexmt, thus they do not switch to the binary mode, and upload doesn't start):

verbose
trace
rexmt 1
binary
connect 192.168.1.1
put WNDR3800-V1.0.0.40.img (or whatever the filename is that you are trying to flash)

If successful, you will see upload progress info for a couple of seconds, then the router will flash itself and reboot automatically. This may take several minutes. Be patient, don't reset or switch off a router!

Notes

Gain access to built-in telnet daemon of the original firmware.

Many Netgear routers have telnet support built-in, but gaining access to it requires an extra step of sending a specially formatted payload to the telnet daemon before it will allow users to log in. Netgear provides the executable called telnetenable.exe for doing just this. It is only available for the "other OS". However, people not employed by Netgear wrote two alternative Programs that do run under Unix. One is written in C and is under the GPLv2 and the other written in Python and is under the MIT License.